Electronic component

ABSTRACT

An electronic component includes a body portion and an external electrode. The external electrode is provided on a surface of the body portion. The external electrode includes a base electrode layer, a first Ni plated layer, and an upper plated layer. The first Ni plated layer is provided on the base electrode layer. The upper plated layer is provided above the first Ni plated layer. The first Ni plated layer includes Ni particles having an average particle size of not more than about 52 nm.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2019-131873 filed on Jul. 17, 2019. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an electronic component.

2. Description of the Related Art

Prior art documents disclosing the configuration of an electroniccomponent include Japanese Patent Laid-Open No. 2017-11142. Anelectronic component described in Japanese Patent Laid-Open No.2017-11142 is a ceramic electronic component in which a base electrodelayer is formed at each of opposing end portions of a ceramic bodyhaving internal electrodes provided therein, and a plated layer isformed on the base electrode layer to form a terminal electrode. A Niplated layer is formed on a surface of the base electrode layer, and aSn plated layer is formed on the Ni plated layer.

In a conventional electronic component, hydrogen atoms are generatedwhen a Ni plated layer is formed on a base electrode layer. The hydrogenatoms diffuse in the base electrode layer, and then also enter a bodyportion. This causes degradation of electrical characteristics of theelectronic component.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide electroniccomponents in each of which degradation of electrical characteristics isable to be reduced or prevented by reduction or prevention of diffusionof hydrogen atoms into a body portion.

An electronic component according to a preferred embodiment of thepresent invention includes a body portion and an external electrode. Theexternal electrode is provided on a surface of the body portion. Theexternal electrode includes a base electrode layer, a first Ni (nickel)plated layer, and an upper plated layer. The first Ni plated layer isprovided on the base electrode layer. The upper plated layer is providedabove the first Ni plated layer. The first Ni plated layer includes Niparticles having an average particle size of not more than about 52 nm.

The above and other elements, features, steps, characteristics, andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an external appearance of anelectronic component according to a first preferred embodiment of thepresent invention.

FIG. 2 is a cross-sectional view of the electronic component in FIG. 1as seen from a direction of arrows of line II-II.

FIG. 3 is a cross-sectional view of the electronic component in FIG. 1as seen from a direction of arrows of line III-III.

FIG. 4 is a schematic cross-sectional view illustrating Ni particles ina Ni plated layer in a portion IV of the electronic component in FIG. 2.

FIG. 5 is a schematic partial cross-sectional view illustrating a methodof measuring an average particle size of the Ni particles in theelectronic component according the first preferred embodiment of thepresent invention.

FIG. 6 is a graph schematically showing an example result of measurementof variations in hydrogen atom concentration in an external electrodewith respect to the depth from a surface of the external electrode, inelectronic components according to comparative examples in a firstexperimental example of the present invention.

FIG. 7 is a graph schematically showing an example result of measurementof variations in hydrogen atom concentration in an external electrodewith respect to the depth from a surface of the external electrode, inelectronic components according to examples of preferred embodiments ofthe present invention in the first experimental example of the presentinvention.

FIG. 8 is a cross-sectional view illustrating an electronic componentaccording a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Electronic components according to preferred embodiments of the presentinvention will be described hereinafter with reference to the drawings.In the following description of each preferred embodiment, the same orcorresponding portions in the drawings are denoted by the same referencecharacters and description thereof will not be repeated.

First Preferred Embodiment

FIG. 1 is a perspective view illustrating an external appearance of anelectronic component according to a first preferred embodiment of thepresent invention. FIG. 2 is a cross-sectional view of the electroniccomponent in FIG. 1 as seen from a direction of arrows of line II-II.FIG. 3 is a cross-sectional view of the electronic component in FIG. 1as seen from a direction of arrows of line FIG. 4 is a schematiccross-sectional view illustrating Ni particles in a Ni plated layer in aportion IV of the electronic component in FIG. 2.

An electronic component 100 according to the first preferred embodimentof the present invention is a multilayer ceramic capacitor, for example,as shown in FIG. 1, but may alternatively be, for example, a multilayernegative temperature coefficient (NTC) thermistor, or a multilayerinductor or ceramic battery (all-solid-state battery).

As shown in FIGS. 1 to 3, electronic component 100 according to thefirst preferred embodiment of the present invention includes a bodyportion 110 and an external electrode 120. In the present preferredembodiment, body portion 110 is a stacked body, and includes a pluralityof dielectric layers 130 and a plurality of internal electrode layers140 that are alternately stacked on one another along a stackingdirection T.

Body portion 110 includes a first main surface 111 and a second mainsurface 112 opposed to each other in stacking direction T, a first sidesurface 113 and a second side surface 114 opposed to each other in awidth direction W orthogonal or substantially orthogonal to stackingdirection T, and a first end surface 115 and a second end surface 116opposed to each other in a length direction L orthogonal orsubstantially orthogonal to both stacking direction T and widthdirection W.

As shown in FIGS. 1 and 2, external electrode 120 is provided on asurface of body portion 110. In electronic component 100 according tothe present preferred embodiment, external electrode 120 includes afirst external electrode 120A and a second external electrode 120B.First external electrode 120A is provided on first end surface 115.Second external electrode 120B is provided on second end surface 116.

The plurality of internal electrode layers 140 include a plurality offirst internal electrode layers 140A connected to first externalelectrode 120A, and a plurality of second internal electrode layers 140Bconnected to second external electrode 120B. As shown in FIG. 2, firstinternal electrode layer 140A includes a facing portion 141A facingsecond internal electrode layer 140B, and an extracted portion 142Aextending to first end surface 115. Second internal electrode layer 140Bincludes a facing portion 141B facing first internal electrode layer140A, and an extracted portion 142B extending to second end surface 116.

As shown in FIGS. 1 to 3, body portion 110 which is a stacked body isdivided into an inner layer portion C, a first outer layer portion X1and a second outer layer portion X2, a first side margin portion S1 anda second side margin portion S2, and a first end margin portion E1 and asecond end margin portion E2.

In inner layer portion C, facing portions 141A of first internalelectrode layers 140A and facing portions 141B of second internalelectrode layers 140B are stacked in stacking direction T to have acapacitance. First outer layer portion X1 is located on a first mainsurface 111 side of inner layer portion C in stacking direction T.Second outer layer portion X2 is located on a second main surface 112side of inner layer portion C in stacking direction T.

First side margin portion S1 is located on a first side surface 113 sideof inner layer portion C in width direction W. Second side marginportion S2 is located on a second side surface 114 side of inner layerportion C in width direction W. First end margin portion E1 is locatedon a first end surface 115 side of inner layer portion C in lengthdirection L. Second end margin portion E2 is located on a second endsurface 116 side of inner layer portion C in length direction L.

It is preferable that each of a dimension of first side margin portionS1 in width direction W, a dimension of second side margin portion S2 inwidth direction W, a dimension of first end margin portion E1 in lengthdirection L, and a dimension of second end margin portion E2 in lengthdirection L are relatively small, from the viewpoint of reducing thesize of electronic component 100, without decrease in insulationresistance of electronic component 100. In the present preferredembodiment, the decrease in insulation resistance of electroniccomponent 100 can be reduced or prevented, as will be described later,thus allowing each of the above-described dimensions to be relativelysmall. For example, each of the dimension of first end margin portion E1in length direction L and the dimension of second end margin portion E2in length direction L is preferably not less than about 10 μm and notmore than about 30 μm.

Each of the plurality of dielectric layers 130 included in inner layerportion C preferably has a thickness not less than about 0.4 μm and notmore than about 0.6 μm, and more preferably not less than about 0.4 μmand not more than about 0.45 μm, for example.

In the present preferred embodiment, electronic component 100 preferablyhas a dimension of not more than about 2.0 mm in length direction L, adimension of not more than about 1.25 mm in width direction W, and adimension of not more than about 1.25 mm in stacking direction T, forexample. The external dimension of electronic component 100 can bemeasured by observing electronic component 100 with an opticalmicroscope.

Dielectric layer 130 is preferably made of a perovskite compoundincluding Ba or Ti, for example. As a material of dielectric layer 130,for example, dielectric ceramics mainly made of BaTiO₃, CaTiO₃, SrTiO₃,CaZrO₃ or the like can be used. A material in which a Mn compound, a Mgcompound, a Si compound, an Fe compound, a Cr compound, a Co compound, aNi compound, an Al compound, a V compound, a rare-earth compound or thelike is added as a sub-component to the above-described main componentmay also be used. The material forming dielectric layer 130 preferablyhas a dielectric constant of not less than about 1000, for example.

Each of the plurality of internal electrode layers 140 preferably has athickness not less than about 0.3 μm and not more than about 1.0 μm, forexample. A coverage rate indicating that each of the plurality ofinternal electrode layers 140 covers dielectric layer 130 without anygap is preferably not less than about 50% and not more than about 95%,for example.

As a material for internal electrode layer 140, one type of metalselected from the group consisting of Ni, Cu, Ag, Pd, and Au, or analloy including this metal, such as, for example, an alloy of Ag and Pd,can preferably be used. Internal electrode layer 140 may includedielectric particles having the same or substantially the samecomposition as that of the dielectric ceramics included in dielectriclayer 130.

As shown in FIG. 2, in the present preferred embodiment, externalelectrode 120 includes a base electrode layer 121, a first Ni (nickel)plated layer 122, a second Ni plated layer 123, and an upper platedlayer 124.

In the present preferred embodiment, base electrode layer 121 is a bakedlayer obtained by applying a conductive paste to body portion 110 whichis a stacked body and baking the same. Base electrode layer 121 includesmetal and glass. The metal included in base electrode layer 121preferably includes, for example, Cu (copper), Ag (silver), Au (gold),Ni (nickel), Sn (tin), or an alloy having any of them. In the presentpreferred embodiment, the metal is more preferably Cu, for example. Theglass preferably includes Si, for example.

Base electrode layer 121 may further include a metal oxide such asBaTiO₃, for example. Base electrode layer 121 may further include aresin component. Examples of the resin component include an epoxy resin,a phenol resin, an urethane resin, a silicone resin, and a polyimideresin. The resin component is preferably an epoxy resin or a phenolresin, for example. When base electrode layer 121 includes metal and aresin component, base electrode layer 121 is preferably, for example, aresin electrode layer having a metal filler.

Base electrode layer 121 may include a plurality of stacked layers. Baseelectrode layer 121 may be a layer fired simultaneously with internalelectrode layer 140.

First Ni plated layer 122 is provided on base electrode layer 121. FirstNi plated layer 122 is substantially made of only metal Ni. In theprocess of forming first Ni plated layer 122, NiO (nickel oxide) may beincluded as an unavoidable impurity in first Ni plated layer 122. Asshown in FIG. 4, first Ni plated layer 122 preferably includes Niparticles 122G having an average particle size of not more than about 52nm, for example.

As shown in FIG. 2, second Ni plated layer 123 is located between firstNi plated layer 122 and upper plated layer 124. Second Ni plated layer123 is substantially made of only metal Ni. In the process of formingsecond Ni plated layer 123, NiO (nickel oxide) may be included as anunavoidable impurity in second Ni plated layer 123. As shown in FIG. 4,second Ni plated layer 123 preferably includes Ni particles 123G havingan average particle size of not less than about 99 nm, for example. Inthe present preferred embodiment, the average particle size of Niparticles 123G of second Ni plated layer 123 is preferably, for example,not less than about 2.3 times the average particle size of Ni particles122G of first Ni plated layer 122.

In the present preferred embodiment, the first Ni plated layer and thesecond Ni plated layer preferably have a total average thicknesspreferably not less than about 0.5 μm and not more than about 10 μm,more preferably not more than about 4.5 μm, and still more preferablynot more than about 3.7 μm, for example. In addition, first Ni platedlayer 122 preferably has a thickness greater than the thickness ofsecond Ni plated layer 123 due to the fact that first Ni plated layer122 occludes more hydrogen atoms, as will be described later. Therelatively large thickness of first Ni plated layer 122 allows first Niplated layer 122 to trap more hydrogen atoms. This, in turn, can reduceor prevent the decrease in insulation resistance, and reduce an averagethickness of the entire external electrode 120 to reduce the size ofelectronic component 100. In the present preferred embodiment, first Niplated layer 122 preferably has a thickness that is not less than about0.03 times and not more than about 14.5 times the thickness of second Niplated layer 123, for example.

Second Ni plated layer 123 may not be included in external electrode120. A preferred embodiment of the present invention in which externalelectrode 120 does not include second Ni plated layer 123 will bedescribed later.

Upper plated layer 124 is provided above first Ni plated layer 122.Specifically, upper plated layer 124 is provided on second Ni platedlayer 123. In the present preferred embodiment, upper plated layer 124is preferably a Sn plated layer, for example. The Sn plated layer issubstantially made of only Sn. In the present preferred embodiment,upper plated layer 124 preferably has a thickness not less than about0.5 μm and not more than about 10 μm, and more preferably not more thanabout 4.5 μm, for example.

Now, a non-limiting example of a method of measuring each of Niparticles 122G of first Ni plated layer 122 and Ni particles 123G ofsecond Ni plated layer 123 in the first preferred embodiment of thepresent invention will be described.

As shown in FIGS. 1, 2 and 4, first, electronic component 100 ispolished to expose a cross section orthogonal or substantiallyorthogonal to width direction W, and the cross section is observed. Afocused ion beam (FIB) device, for example, is used to polish electroniccomponent 100. When observing the cross section, an average particlesize of each of Ni particles 122G of first Ni plated layer 122 and Niparticles 123G of second Ni plated layer 123 is measured with amicroscope.

As shown in FIGS. 2 and 4, a measurement position P1 of Ni particles122G in first Ni plated layer 122 is a central portion in stackingdirection T, at a distance of about 100 nm from base electrode layer 121in length direction L.

FIG. 5 is a schematic partial cross-sectional view illustrating themethod of measuring the average particle size of the Ni particles in theelectronic component according the first preferred embodiment of thepresent invention. As shown in FIG. 5, on measurement position P1, atotal length of ten Ni particles 122G adjacent to one another in firstNi plated layer 122 is measured. The total length is divided by 10, tomeasure the average particle size of Ni particles 122G in first Niplated layer 122.

As shown in FIGS. 2 and 4, a measurement position P2 of Ni particles123G in second Ni plated layer 123 is a central portion in stackingdirection T, at a distance of 100 nm from upper plated layer 124 inlength direction L. On measurement position P2, a total length of ten Niparticles 123G adjacent to one another in second Ni plated layer 123 ismeasured. The total length is divided by 10, to measure the averageparticle size of Ni particles 123G in second Ni plated layer 123.

A method of measuring the dimensions of the components will now bedescribed. The thickness of each of dielectric layers 130 and internalelectrode layers 140 included in inner layer portion C is measured asfollows. First, electronic component 100 is polished to expose a crosssection orthogonal or substantially orthogonal to length direction L.The exposed cross section is observed with a scanning electronmicroscope. Next, measurement is performed of the thickness of each ofdielectric layers 130 and internal electrode layers 140 on five lines intotal, i.e., a center line along stacking direction T passing throughthe center or the approximate center of the exposed cross section aswell as two lines drawn from this center line toward one side at regularintervals and two lines drawn from this center line toward the otherside at regular intervals. An average value of the five measurementvalues of dielectric layers 130 is defined as the thickness ofdielectric layer 130. An average value of the five measurement values ofinternal electrode layers 140 is defined as the thickness of internalelectrode layer 140.

In each of an upper portion, a central portion, and a lower portionlocated on a boundary line that divides the exposed cross section intofour portions in stacking direction T, measurement may be performed ofthe thickness of each of dielectric layers 130 and internal electrodelayers 140 on the above-described five lines, and an average value ofthe measurement values of dielectric layers 130 may be defined as thethickness of dielectric layer 130 and an average value of themeasurement values of internal electrode layers 140 may be defined asthe thickness of internal electrode layer 140.

Each of a dimension of body portion 110 which is a stacked body in widthdirection W and a dimension of body portion 110 in stacking direction Tis measured by observing, with an optical microscope, a portion of bodyportion 110 not covered with first external electrode 120A and secondexternal electrode 120B. A measurement position is a central portion inlength direction L.

A dimension of body portion 110 which is a stacked body in lengthdirection L is measured as follows. First, electronic component 100 ispolished to expose a cross section orthogonal or substantiallyorthogonal to width direction W. The exposed cross section is observedwith a microscope and the dimension is measured. A measurement positionis a central portion in stacking direction T.

Each of a dimension of first outer layer portion X1 in stackingdirection T and a dimension of second outer layer portion X2 in stackingdirection T is measured as follows. First, electronic component 100 ispolished to expose a cross section orthogonal or substantiallyorthogonal to width direction W. The exposed cross section is observedwith a microscope and each of the above-described dimensions ismeasured. A measurement position is the central portion in lengthdirection L.

Each of a dimension of first end margin portion E1 in length direction Land a dimension of second end margin portion E2 in length direction L ismeasured as follows. First, electronic component 100 is polished toexpose a cross section orthogonal or substantially orthogonal to widthdirection W. The exposed cross section is observed with a microscope andeach of the above-described dimensions is measured. Measurementpositions are an upper portion, a central portion and a lower portionlocated on a boundary line that divides the exposed cross section intofour parts in stacking direction T. An average value of the measurementvalues of first end margin portion E1 at these three locations isdefined as the dimension of first end margin portion E1 in lengthdirection L, and an average value of the measurement values of secondend margin portion E2 at these three locations is defined as thedimension of second end margin portion E2 in length direction L.

The thickness of each of first side margin portion S1 and second sidemargin portion S2 is measured as follows. First, electronic component100 is polished to expose a cross section orthogonal or substantiallyorthogonal to length direction L. The exposed cross section is observedwith a microscope and measured. Measurement positions are an upperportion, a central portion and a lower portion located on a boundaryline that divides the exposed cross section into four parts in stackingdirection T. An average value of the measurement values of first sidemargin portion S1 at these three locations is defined as the dimensionof first side margin portion S1 in width direction W, and an averagevalue of the measurement values of second side margin portion S2 atthese three locations is defined as the dimension of second side marginportion S2 in width direction W.

The thickness of base electrode layer 121 is measured as follows. First,electronic component 100 is polished to expose a cross sectionorthogonal or substantially orthogonal to width direction W. The exposedcross section is observed with a microscope and measured. A measurementposition is the central portion in stacking direction T.

The thickness of each of first Ni plated layer 122, second Ni platedlayer 123 and upper plated layer 124 is measured as follows. First,electronic component 100 is polished with the FIB device to expose across section orthogonal or substantially orthogonal to width directionW. The exposed cross section is observed with a microscope, and each ofthe above-described thicknesses is measured. A measurement position isthe central portion in stacking direction T. The thickness of upperplated layer 124 may be measured with a fluorescent X-ray film thicknessmeter.

A non-limiting example of a method of manufacturing electronic component100 according to the first preferred embodiment of the present inventionwill be described below. The method of manufacturing electroniccomponent 100 described below is a method of manufacturing a multilayerceramic capacitor, for mass-producing a plurality of multilayer ceramiccapacitors simultaneously by collectively performing the processingtreatment halfway through the manufacturing process to fabricate amother stacked body, and thereafter, cutting and dividing the motherstacked body into individual pieces, and further performing theprocessing treatment on a divided soft stacked body.

When electronic component 100 which is a multilayer ceramic capacitor ismanufactured, ceramic slurry is first prepared. Specifically, a ceramicpowder, a binder, a solvent and the like are mixed at a prescribedblending ratio, to thus form the ceramic slurry.

Next, a ceramic green sheet is formed. Specifically, the ceramic slurryis shaped into a sheet on a carrier film using a die coater, a gravurecoater, a microgravure coater or the like, for example, to thus form theceramic green sheet.

Next, a mother sheet is formed. Specifically, a conductive paste isprinted on the ceramic green sheet using a screen printing method, agravure printing method or the like, for example, so as to have aprescribed pattern, to thus form the mother sheet having the prescribedconductive pattern on the ceramic green sheet.

In addition to the mother sheet having the conductive pattern, a ceramicgreen sheet not having a conductive pattern is also prepared as themother sheet.

Next, the mother sheets are stacked. Specifically, the prescribed numberof mother sheets forming first outer layer portion X1 and not having theconductive pattern are stacked, and a plurality of mother sheets forminginner layer portion C and having the conductive pattern are sequentiallystacked on the prescribed number of mother sheets, and the prescribednumber of mother sheets forming second outer layer portion X2 and nothaving the conductive pattern are stacked on the plurality of mothersheets. A group of mother sheets are thereby formed.

Next, the group of mother sheets are compression-bonded. The group ofmother sheets are pressurized and compression-bonded along stackingdirection T using isostatic pressing or rigid body pressing, forexample, to thus form a mother stacked body.

Next, the mother stacked body is cut. Specifically, the mother stackedbody is cut in a matrix manner using press-cutting or dicing, forexample, and divided into a plurality of soft stacked bodies.

Next, the soft stacked bodies are barrel-polished. Specifically, thesoft stacked bodies are put into a small box called a “barrel,” togetherwith a media ball having a hardness higher than that of the ceramicmaterial, and the barrel is rotated, to thus round corner portions andridge portions of the soft stacked bodies to have a curved surface.

Next, the soft stacked bodies are fired. Specifically, the soft stackedbodies are heated to a prescribed temperature, to thus fire thedielectric ceramics material. The firing temperature is set asappropriate depending on the type of the dielectric ceramics material,and is preferably set to be within the range of not less than about 900°C. and not more than about 1300° C., for example.

Next, a base electrode layer is formed on a surface of body portion 110which is a stacked body. Specifically, base electrode layer 121 of eachof first external electrode 120A and second external electrode 120B isformed, for example, using various types of thin film formation methods,various types of printing methods, a dipping method or the like. Forexample, when the base electrode layer is formed using the dippingmethod, a conductive paste is applied to first end surface 115 andsecond end surface 116 of body portion 110, and thereafter, theconductive paste is baked. The conductive paste includes an organicsolvent, metal particles and glass. In the present preferred embodiment,the baking temperature is preferably about 840° C., for example.

Next, first Ni plated layer 122, second Ni plated layer 123 and upperplated layer 124 are sequentially formed by electrolytic plating, forexample, to cover base electrode layer 121 by the plating treatment.Each of the electrodes is formed, and thus, first external electrode120A and second external electrode 120B are formed.

In the present preferred embodiment, first Ni plated layer 122 andsecond Ni plated layer 123 are formed by electrolytic plating using abarrel electroplating device, for example. The average particle size ofeach of first Ni particles 122G in first Ni plated layer 122 and secondNi particles 123G in second Ni plated layer 123 can be set asappropriate by controlling processing conditions, such as the metal ionconcentration in a plating solution used in the electrolytic plating,the type and concentration of an additive contained in the platingsolution, the current value of a current applied during the electrolyticplating, the treatment temperature, or the strength of agitation of theplating solution. For example, the average particle size of the Niparticles decreases as the concentration of the additive in the platingsolution increases. The average particle size of the Ni particlesdecreases as the current value of the applied current increases. Theaverage particle size of the Ni particles decreases as the temperatureof the plating solution increases.

Table 1 below shows example processing conditions for electrolyticplating using a barrel electroplating device, when an average particlesize of Ni plating is set by controlling the processing conditions.Saccharin was used as an additive in Table 1 below.

TABLE 1 Processing Processing Processing Condition 1 Condition 2Condition 3 Concentration of 1 1 1 Additive [g/L] Temperature of Plating60 60 60 Solution [° C.] Current Value [A] 15 10 5 Diameter of Barrel[mm] 67 67 67 Amount of Conductive 60 60 60 Medium [cc] Particle Size ofNi 37 52 78 Particles [nm]

As shown in Table 1, an applied current has different current valuesamong a processing condition 1, a processing condition 2, and aprocessing condition 3. As shown in Table 1, it can be seen that theparticle size of Ni particles in the Ni plating decreases as the currentvalue increases.

In addition to the saccharin, benzenesulfonic acid, benzothiazole,thiourea, benzalacetone, polyethylene glycol, butynediol, propargylalcohol or the like, for example, can be used as the additive.

When the first Ni plated layer and the second Ni plated layer are formedby electrolytic plating, hydrogen atoms are generated due to a reductionreaction of hydrogen ions. The hydrogen atoms are occluded in each offirst Ni plated layer 122 and the second Ni plated layer. The occludedhydrogen atoms are able to freely move through external electrode 120.

Through the series of steps described above, electronic component 100according to the first preferred embodiment of the present inventionwhich is a multilayer ceramic capacitor is manufactured.

A first experimental example will be described below, in whichvariations in insulation resistance and solder wettability after anaccelerated test in electronic component 100 was evaluated, while eachof an average particle size D_(N1) of Ni particles 122G in first Niplated layer 122, an average particle size D_(N2) of Ni particles 123Gin second Ni plated layer 123, a thickness T_(N1) of first Ni platedlayer 122, and a thickness T_(N2) of second Ni plated layer 123 wasvaried in the electronic component.

In this experimental example, the electronic component according to eachexample and each comparative example was manufactured such that theelectronic component had a dimension of about 1.10 mm in lengthdirection L, a dimension of about 0.600 mm in width direction W, and adimension of about 0.600 mm in stacking direction T. The electroniccomponent according to each example and each comparative example wasalso manufactured such that each of the plurality of dielectric layers130 included in inner layer portion C had a thickness of about 0.60 μm,each of the plurality of internal electrode layers 140 included in innerlayer portion C had a thickness of about 0.50 μm, each of first endmargin portion E1 and second end margin portion E2 had a dimension ofabout 40 μm in length direction L, each of first side margin portion S1and second side margin portion S2 had a dimension of about 20 μm inwidth direction W, and each of first outer layer portion X1 and secondouter layer portion X2 had a dimension of about 30 μm in stackingdirection T.

In this experimental example, “SMI-3050R” manufactured by SIINanoTechnology Inc. was used as an FIB device used for the measurementof the average particle size of the Ni particles.

The accelerated test was conducted by applying a voltage to theelectronic component in a bath having high temperature and highhumidity. First, the electronic component according to each example andeach comparative example was placed in a bath having an atmosphere ofabout 125° C. and a relative humidity of about 95% RH. Then, theelectronic component placed in the bath was held for about 100 hourswhile a DC voltage of about 1 V was applied between first externalelectrode 120A and second external electrode 120B. The electroniccomponent thus treated was measured for its insulation resistance value,and was determined to have “failed” if the insulation resistance valuewas about 90% or less than the insulation resistance value in a statebefore the accelerated test.

The evaluation of solder wettability was performed with a solder globulebalancing method using a solder checker (model number: SAT-5100)manufactured by Rhesca Co., Ltd. Aging was performed for about fourhours using an unsaturated PCT device under an atmosphere of atemperature of about 105° C., a relative humidity of not more than about100% RH, and an atmospheric pressure of about 1.22×10⁵ Pa. The solderhad a composition of Sn-3.0Ag-0.5Cu, the solder had a mass of about25±2.5 mg, an iron core had a diameter of about 2 mm, flux containedabout 25 wt % of rosin and 2-propanol (isopropyl alcohol), the amount offlux on a solder side was about 20±1 μL, the dipping speed was about 1mm/s, the dipping depth was about 0.1 mm, the dipping time was about 10seconds, the measurement range was about 5 mN, and the test temperaturewas about 230±3° C. Under the conditions described above, a time T₀between when the electronic component made contact with the solder andwhen the angle of contact with the solder returned to about 90 degreeswas measured. As a result of the measurement, the electronic componentwas determined to be “passed” if its time T₀ was not longer than about4.0 seconds, and determined to have “failed” if its time T₀ was longerthan about 4.0 seconds.

Tables 2 to 4 below show results of the evaluation of insulationresistance and solder wettability after the accelerated test in theelectronic component according to each example and each comparativeexample. In the evaluation results of insulation resistance after theaccelerated test in Tables 2 to 4, “A” indicates that zero electroniccomponents were determined to have “failed,” “B” indicates that not lessthan one and not more than three electronic components were determinedto have “failed,” and “C” indicates that not less than four electroniccomponents were determined to have “failed,” as a result of measurementof insulation resistance values of ten samples for each example and eachcomparative example. In the evaluation results of solder wettability inTables 2 to 4, “A” indicates that zero electronic components weredetermined to have “failed,” “B” indicates that not less than one andnot more than three electronic components were determined to have“failed,” and “C” indicates that not less than four electroniccomponents were determined to have “failed,” as a result of measurementof time T₀ of ten samples for each example and each comparative example.

TABLE 2 Com. Com. Com. Com. Com. Com. Com. Com. Ex. 1 Ex. 2 Ex. 3 Ex. 4Ex. 5 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 6 Ex. 7Ex. 8 Average Particle 15 22 35 44 52 82 105 108 111 77 21 21 46 39 9865 76 Size D_(N1) [nm] of Ni Particles in First Ni Plated Layer AverageParticle 102 201 158 99 323 194 104 85 61 48 32 357 218 43 301 188 304Size D_(N2) [nm] of Ni Particles in Second Ni Plated Layer D_(N2)/D_(N1)6.8 9.1 4.5 2.3 6.2 2.4 1.0 0.8 0.5 0.6 1.5 17 4.7 1.1 3.1 2.9 4.0Insulation A A A A A B C C C B A A A A C B B Resistance AfterAccelerated Test Solder A A A A A A A B C C C A A C A A A Wettability

TABLE 3 Com. Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex.18 Ex. 9 Average Particle 35 35 35 35 35 35 35 35 35 — Size D_(N1) [nm]of Ni Particles in First Ni Plated Layer Average Particle — 250 250 250250 250 250 250 250 250 Size D_(N2) [nm] of Ni Particles in Second NiPlated Layer Thickness T_(N1) 3.1 2.6 2.2 1.8 1.5 1.2 0.9 0.6 0.1 0 [μm]of First Ni Plated Layer Thickness T_(N2) 0 0.3 0.9 1.2 1.4 1.6 2.1 2.52.9 2.9 [μm] of Second Ni Plated Layer T_(N1)/(T_(N1) + T_(N2)) 100.089.7 71.0 60.0 51.7 42.9 30.0 19.4 3.3 0.0 [%] T_(N1)/T_(N2) — 8.67 2.441.50 0.11 0.75 0.43 0.24 0.03 0.00 Insulation A A A A A A A A A CResistance After Accelerated Test Solder C A A A A A A A A A Wettability

TABLE 4 Com. Ex. 19 Ex. 20 Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Ex.10 Average Particle 35 35 35 35 35 35 35 35 — Size D_(N1) [nm] of NiParticles in First Ni Plated Layer Average Particle — 120 120 120 120120 120 120 120 Size D_(N2) [nm] of Ni Particles in Second Ni PlatedLayer Thickness T_(N1) 3.1 2.9 2.5 1.8 1.2 0.7 0.6 0.1 0 [μm] of FirstNi Plated Layer Thickness T_(N2) 0 0.2 0.7 1.1 1.7 2.3 2.5 3.0 3.1 [μm]of Second Ni Plated Layer T_(N1)/(T_(N1) + T_(N2)) 100.0 93.5 78.1 62.141.4 23.3 19.4 3.2 0.0 [%] T_(N1)/T_(N2) — 14.5 1.63 1.50 0.71 0.30 0.240.03 0 Insulation A A A A A A A A C Resistance After Accelerated TestSolder C A A A A A A A A Wettability

As shown in Tables 2 to 4, the evaluation of insulation resistance afterthe accelerated test is “B” or “C” in Comparative Examples 1 to 8 whereaverage particle size D_(N1) of the Ni particles in the first Ni platedlayer exceeds about 52 nm, and in Comparative Examples 9 and 10 that donot include the first Ni plated layer. That is, the insulationresistance tends to decrease in the electronic component according toeach comparative example.

The reason for the decrease in insulation resistance may be as set forthbelow. As described above, hydrogen atoms are generated when the firstNi plated layer and the second Ni plated layer are formed byelectrolytic plating. In the electronic component according to eachcomparative example described above, the hydrogen atoms are able tofreely move through the external electrode having a metal component, andthe hydrogen atoms also diffuse into the body portion. The hydrogenatoms that have diffused into the body portion cause a decrease ininsulation resistance of the body portion.

As shown in Tables 2 to 4, however, the evaluation of insulationresistance after the accelerated test is “A” in Examples 1 to 26, whereaverage particle size D_(N1) of the Ni particles in the first Ni platedlayer is not more than about 52 nm. That is, the decrease in insulationresistance is reduced or prevented in the electronic component accordingto each example.

The reason for the reduction or prevention of the decrease in insulationresistance may be as set forth below. FIG. 6 is a graph schematicallyshowing an example result of measurement of variations in hydrogen atomconcentration in the external electrode with respect to the depth fromthe surface of the external electrode, in the electronic componentsaccording to the comparative examples in the first experimental exampleof the present invention. FIG. 7 is a graph schematically showing anexample result of measurement of variations in hydrogen atomconcentration in the external electrode with respect to the depth fromthe surface of the external electrode, in the electronic componentsaccording to the examples in the first experimental example of thepresent invention.

FIGS. 6 and 7 show results of measurement in electronic componentsincluding both the first Ni plated layer and the second Ni plated layer.The hydrogen atom concentration can be measured with dynamic-secondaryion mass spectrometry (D-SIMS), for example. In this experimentalexample, the hydrogen atom concentration was measured with D-SIMS using“IMS-6f” manufactured by Cameca.

As shown in FIG. 6, in the electronic components according to thecomparative examples, the hydrogen atom concentration in the first Niplated layer and the hydrogen atom concentration in the second Ni platedlayer are equal or substantially equal to each other in the externalelectrode. In contrast, as shown in FIG. 7, in the electronic componentaccording to each example, the hydrogen atom concentration in the firstNi plated layer is the highest in the external electrode. Moreover, asshown in FIGS. 6 and 7, the hydrogen atom concentration in the baseelectrode layer of the electronic components according to the examplesis lower than the hydrogen atom concentration in the base electrodelayer of the electronic components according to the comparativeexamples.

As shown in FIGS. 6 and 7, therefore, in the electronic componentaccording to each example in this experimental example, first Ni platedlayer 122 traps the hydrogen atoms, which leads to a relatively smallernumber of hydrogen atoms diffusing into base electrode layer 121, whichin turn is believed to lead to a relatively smaller number of hydrogenatoms diffusing into body portion 110 through base electrode layer 121.A smaller number of hydrogen atoms in body portion 110 leads to asmaller number of hydrogen atoms diffusing in dielectric layer 130. Itis believed that the decrease in insulation resistance is reduced orprevented in this manner in electronic component 100 according to eachexample described above.

As shown in Tables 2 to 4, in each example, the first Ni plated layerincludes Ni particles having an average particle size of not more thanabout 52 nm, and thus includes Ni particles having a relatively smallparticle size. That is, the first Ni plated layer in each example has alarge grain boundary area of Ni particles. It is believed that thehydrogen atoms diffusing in external electrode 120 tend to accumulate onan interface between the Ni particles in the first Ni plated layer ineach example.

Results of the evaluation of solder wettability will now be described.As shown in Table 2, the evaluation of solder wettability is “A” in theelectronic components according to Examples 1 to 5, 7, and 8 whereaverage particle size D_(N2) of the Ni particles in the second Ni platedlayer is not less than about 2.3 times average particle size D_(N1) ofthe Ni particles in the first Ni plated layer. On the other hand, theevaluation of solder wettability is “C” in the electronic componentsaccording to Examples 6 and 9 where average particle size D_(N2) of theNi particles in the second Ni plated layer is less than about 2.3 timesaverage particle size D_(N1) of the Ni particles in the first Ni platedlayer. That is, it can be seen that the solder wettability is improvedwhen average particle size D_(N2) of the Ni particles in the second Niplated layer is not less than about 2.3 times average particle sizeD_(N1) of the Ni particles in the first Ni plated layer.

The reason for the improvement in solder wettability may be as set forthbelow. When solder adheres to external electrode 120, the solder meltsupper plated layer 124, and then wets and spreads over second Ni platedlayer 123. In the electronic components according to Examples 1 to 5, 7,and 8, Ni particles 123G of second Ni plated layer 123 have a relativelylarge average particle size due to the configuration described above,and therefore, oxidation of Ni is reduced or prevented in second Niplated layer 123. It is believed that the wettability is improved on thesurface of second Ni plated layer 123 where the oxidation is reduced orprevented. This, in turn, is believed to improve the solder wettabilitywhen solder adheres to external electrode 120.

As shown in Tables 3 and 4, the decrease in insulation resistance isreduced or prevented in the electronic components according to Examples11 to 18 and 20 to 26 where thickness T_(N1) of the first Ni platedlayer is not less than about 0.03 times thickness T_(N2) of the secondNi plated layer. The solder wettability is improved in the electroniccomponents according to Examples 10 to 26 where thickness T_(N1) of thefirst Ni plated layer is not more than about 14.5 times thickness T_(N2)of the second Ni plated layer.

As shown in Table 2, the solder wettability is improved in theelectronic components according to Examples 1 to 5, 7, and 8 whereaverage particle size D_(N2) of the Ni particles in the second Ni platedlayer is not less than about 99 nm, as compared to the electroniccomponents according to Examples 6 and 9 where average particle sizeD_(N2) of the Ni particles in the second Ni plated layer is less thanabout 99 nm.

As described above, in electronic component 100 according to the firstpreferred embodiment of the present invention, first Ni plated layer 122includes Ni particles having an average particle size of not more thanabout 52 nm.

Therefore, the diffusion of hydrogen atoms from first Ni plated layer122 into body portion 110 can be reduced or prevented. This, in turn,can reduce or prevent the degradation of electrical characteristics ofelectronic component 100.

In the present preferred embodiment, the average particle size of Niparticles 123G of second Ni plated layer 123 is not less than about 2.3times the average particle size of the Ni particles making up first Niplated layer 122.

Therefore, the oxidation is reduced or prevented on the surface ofsecond Ni plated layer 123, and the solder wettability is thus improved.This, in turn, can improve the solder wettability of external electrode120.

In the present preferred embodiment, first Ni plated layer 122 has athickness that is not less than about 0.3 times the thickness of secondNi plated layer 123.

Therefore, first Ni plated layer 122 capable of trapping the hydrogenatoms is provided to have a prescribed thickness, and is thus able totrap more hydrogen atoms. This, in turn, can reduce or prevent thedegradation of electrical characteristics of electronic component 100.

In the present preferred embodiment, first Ni plated layer 122 has athickness that is not more than about 14.5 times the thickness of secondNi plated layer 123.

Therefore, a prescribed thickness of second Ni plated layer 123 can beensured, and exposure of first Ni plated layer 122 together with secondNi plated layer 123 can thus be reduced or prevented when upper platedlayer 124 is melted due to the adhesion of solder. Thus, the decrease insolder wettability of external electrode 120 can be reduced orprevented.

In the present preferred embodiment, second Ni plated layer 123 includesNi particles having an average particle size of not less than about 99nm.

Therefore, the oxidation of Ni particles 123G on the surface of secondNi plated layer 123 is reduced or prevented, leading to improved solderwettability of second Ni plated layer 123. The solder wettability ofexternal electrode 120 can thus be improved.

In the present preferred embodiment, base electrode layer 121 includesmetal. Therefore, a prescribed electrical conductivity can be ensured inbase electrode layer 121.

In the present preferred embodiment, base electrode layer 121 mayfurther include a metal oxide. Therefore, when body portion 110 and baseelectrode layer 121 are formed by simultaneous firing, securing powerbetween base electrode layer 121 and body portion 110 can be improved.This, in turn, can reduce the thickness of the entire external electrode120.

In the present preferred embodiment, base electrode layer 121 furtherincludes glass. Therefore, when applying a conductive paste to bodyportion 110 to provide base electrode layer 121, the glass enablessecuring of a sintering aid included in the conductive paste and bodyportion 110 to each other at sufficient strength.

In the present preferred embodiment, base electrode layer 121 mayfurther include a resin component. Therefore, when electronic component100 is mounted on a substrate, base electrode layer 121 can haveimproved strength with respect to deflection of the substrate.

In the present preferred embodiment, the metal included in baseelectrode layer 121 includes, for example, Cu (copper), Ag (silver), Au(gold), Ni (nickel), Sn (tin), or an alloy having any of them.

Therefore, base electrode layer 121 can have a relatively highelectrical conductivity.

Electronic component 100 according to the present preferred embodimentis a multilayer ceramic capacitor, for example.

In electronic component 100 in the present preferred embodiment, thediffusion of hydrogen atoms into base electrode layer 121 is reduced orprevented. Thus, reduction of the ceramics included in body portion 110of the multilayer ceramic capacitor with the hydrogen atoms can bereduced or prevented. This, in turn, can reduce or prevent the decreasein insulation resistance of the multilayer ceramic capacitor due to thereduction of the ceramics with the hydrogen atoms.

Second Preferred Embodiment

An electronic component according to a second preferred embodiment ofthe present invention will be described below. The electronic componentaccording to the second preferred embodiment of the present invention isdifferent from electronic component 100 according to the first preferredembodiment of the present invention in that the external electrode doesnot include the second Ni plated layer. Thus, description of aconfiguration the same as or similar to that of the electronic componentaccording to the first preferred embodiment of the present inventionwill not be repeated.

FIG. 8 is a cross-sectional view illustrating the electronic componentaccording to the second preferred embodiment of the present invention.FIG. 8 is illustrated in the same cross section as FIG. 2. As shown inFIG. 8, in an electronic component 200 according to the second preferredembodiment of the present invention, upper plated layer 124 is providedon a first Ni plated layer 222.

A second experimental example will now be described, in which insulationresistance after an accelerated test in electronic component 200according to the present preferred embodiment was evaluated. Eachmeasurement condition and a method of evaluating insulation resistancein the second experimental example are the same as or similar to thoseof the first experimental example in the first preferred embodiment ofthe present invention.

Tables 5 below shows results of the evaluation of insulation resistanceafter the accelerated test in the electronic component according to eachexample and each comparative example in the second experimental example.

TABLE 5 Com. Com. Com. Com. Com. Ex. 27 Ex. 28 Ex. 29 Ex. 30 Ex. 31 Ex.32 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Average Particle 15 21 22 35 44 5282 105 108 111 77 Size D_(N1) [nm] of Ni Particles in First Ni PlatedLayer Insulation A A A A A A B C C C B Resistance After Accelerated Test

As shown in Table 5, the evaluation of insulation resistance after theaccelerated test is “B” or “C” in Comparative Examples 11 to 15 whereaverage particle size D_(N1) of the Ni particles in the first Ni platedlayer exceeds about 52 nm. On the other hand, the evaluation ofinsulation resistance after the accelerated test is “A” in Examples 27to 32 where average particle size D_(N1) of the Ni particles in thefirst Ni plated layer is not more than about 52 nm. That is, also in thesecond experimental example, the decrease in insulation resistance isreduced or prevented in the electronic component according to eachexample.

From the above, also in the second preferred embodiment of the presentinvention, since first Ni plated layer 222 includes Ni particles 122Ghaving an average particle size of not more than about 52 nm, thediffusion of hydrogen atoms from first Ni plated layer 222 into bodyportion 110 can be reduced or prevented. This, in turn, can reduce orprevent the degradation of characteristics of electronic component 100.

In the above description of the preferred embodiments, combinablecomponents may be combined together.

Although preferred embodiments of the present invention have beendescribed and illustrated in detail, it is understood that the same isby way of illustration and example only and is not to be taken by way oflimitation, the scope of the present invention being interpreted by theterms of the appended claims.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. An electronic component comprising: a bodyportion; and an external electrode provided on a surface of the bodyportion; wherein the external electrode including a base electrodelayer, a first Ni plated layer provided on the base electrode layer, andan upper plated layer provided above the first Ni plated layer; and thefirst Ni plated layer includes Ni particles having an average particlesize of not more than about 52 nm.
 2. The electronic component accordingto claim 1, wherein the external electrode further includes a second Niplated layer between the first Ni plated layer and the upper platedlayer; and an average particle size of Ni particles included in thesecond Ni plated layer is not less than about 2.3 times the averageparticle size of the Ni particles included in the first Ni plated layer.3. The electronic component according to claim 2, wherein the first Niplated layer has a thickness not less than about 0.03 times a thicknessof the second Ni plated layer.
 4. The electronic component according toclaim 3, wherein the first Ni plated layer has a thickness not more thanabout 14.5 times the thickness of the second Ni plated layer.
 5. Theelectronic component according to claim 1, wherein the externalelectrode further includes a second Ni plated layer between the first Niplated layer and the upper plated layer; and the second Ni plated layerincludes Ni particles having an average particle size of not less thanabout 99 nm.
 6. The electronic component according to claim 5, whereinthe first Ni plated layer has a thickness not less than about 0.03 timesa thickness of the second Ni plated layer.
 7. The electronic componentaccording to claim 6, wherein the first Ni plated layer has a thicknessnot more than about 14.5 times the thickness of the second Ni platedlayer.
 8. The electronic component according to claim 1, wherein thebase electrode layer includes metal.
 9. The electronic componentaccording to claim 8, wherein the base electrode layer further includesa metal oxide.
 10. The electronic component according to claim 8,wherein the base electrode layer further includes glass.
 11. Theelectronic component according to claim 10, wherein the base electrodelayer further includes a metal oxide.
 12. The electronic componentaccording to claim 8, wherein the base electrode layer further includesa resin component.
 13. The electronic component according to claim 12,wherein the base electrode layer further includes a metal oxide.
 14. Theelectronic component according to claim 8, wherein the base electrodelayer further includes glass and a resin component.
 15. The electroniccomponent according to claim 14, wherein the base electrode layerfurther includes a metal oxide.
 16. The electronic component accordingto claim 8, wherein the metal includes Cu, Ag, Au, Ni, Sn, or an alloyincluding any of Cu, Ag, Au, Ni, and Sn.
 17. The electronic componentaccording to claim 1, wherein the electronic component is a multilayerceramic capacitor.
 18. The electronic component according to claim 1,wherein the body portion is a stacked body including a plurality ofdielectric layers and a plurality of internal electrode layers that arealternately stacked on one another.
 19. The electronic componentaccording to claim 18, wherein the plurality of internal electrodelayers are connected to the external electrode.
 20. The electroniccomponent according to claim 18, wherein each of the plurality ofdielectric layers has a thickness of not less than about 0.4 μm and notmore than about 0.6 μm.